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DTC P1259: VTEC System Malfunction (2000-2003 models)

Special Tools Required 

NOTE: Before you troubleshoot, record all freeze data and review the general troubleshooting information (see GENERAL TROUBLESHOOTING INFORMATION ).
  1. Reset the engine control module (ECM) (see HOW TO RESET THE ECM ).
  2. Check the engine oil level, and refill if necessary.
  3. Start the engine. Hold the engine speed at 3,000 RPM without load (in neutral) until the radiator fan comes on.
  4. Road test the vehicle:

    Accelerate in 1st gear to an engine speed over 6,000 RPM. Hold that engine speed for at least 2 seconds. If DTC P1259 is not repeated during the first road test, repeat this test two more times.

    Is DTC P1259 indicated? 

    1. YES -  Go to step 5.
    2. NO -  Intermittent failure, system is OK at this time. Check for poor connections or loose wires at the rocker arm oil control solenoid (VTEC solenoid valve), the rocker arm oil pressure switch (VTEC oil pressure switch), and the ECM.
  5. Turn the ignition switch OFF.
  6. Disconnect the rocker arm oil pressure switch (VTEC oil pressure switch) 2P connector.
  7. At the switch side, check for continuity on the rocker arm oil pressure switch (VTEC oil pressure switch) between rocker arm oil pressure switch (VTEC oil pressure switch) 2P connector terminals No. 1 and No. 2.
    Fig 1: Checking Continuity On Rocker Arm Oil Pressure Switch (VTEC Oil Pressure Switch)
    G03692702Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES -  Go to step 8.
    2. NO -  Replace the rocker arm oil pressure switch (VTEC oil pressure switch).
  8. Turn the ignition switch ON (II).
  9. Measure the voltage between the rocker arm oil pressure switch (VTEC oil pressure switch) harness 2P connector terminal No. 1 and body ground.
    Fig 2: Measuring Voltage Between Rocker Arm Oil Pressure Switch
    G03692703Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    1. YES -  Go to step  14.
    2. NO -  Inspect for an open or short to ground in the wire between the rocker arm oil pressure switch (VTEC oil pressure switch) and the ECM (C10). If the wire is OK, substitute a known-good ECM (see HOW TO SUBSTITUTE THE ECM FOR TESTING PURPOSES ) and recheck.
  10. Measure voltage between ECM connector terminal C10 and body ground.
    Fig 3: Measuring Voltage Between ECM Connector Terminal C10 And Body Ground
    G03692704Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    1. YES -  Repair open in the wire between the rocker arm oil pressure switch (VTEC oil pressure switch) and the ECM.
    2. NO -  Go to step 11.
  11. Turn the ignition switch OFF.
  12. Disconnect the ECM connector C (31P).
  13. Check for continuity between ECM connector terminal C10 and body ground.
    Fig 4: Checking Continuity Between ECM Connector Terminal C10 And Body Ground
    G03692705Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES -  Repair short in the wire between the rocker arm oil pressure switch (VTEC oil pressure switch) and the ECM(C9).
    2. NO -  Substitute a known-good ECM (see HOW TO SUBSTITUTE THE ECM FOR TESTING PURPOSES ) and recheck. If the symptom/indication goes away, replace the original ECM (see ECM REPLACEMENT ).
  14. Measure voltage between rocker arm oil pressure switch (VTEC oil pressure switch) 2P connector terminals No. 1 and No. 2.
    Fig 5: Measuring Voltage Between Rocker Arm Oil Pressure Switch
    G03692706Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    1. YES -  Go to step 15.
    2. NO -  Repair open in the wire between the rocker arm oil pressure switch (VTEC oil pressure switch) and G101.
  15. Turn the ignition switch OFF.
  16. Disconnect the rocker arm oil control solenoid (VTEC solenoid valve) 1P connector.
  17. At the valve side, measure resistance between the rocker arm oil control solenoid (VTEC solenoid valve) 1P connector and body ground.
    Fig 6: Disconnecting Rocker Arm Oil Control Solenoid (VTEC Solenoid Valve) 1P Connector
    G03692707Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there 14-30 Ω ? 

    1. YES -  Go to step 18.
    2. NO -  Replace the rocker arm oil control solenoid (VTEC solenoid valve).
  18. Remove the rocker arm oil pressure switch (VTEC oil pressure switch) (A) and install the special tools as shown, then reinstall the rocker arm oil pressure switch (VTEC oil pressure switch).
    NOTE: Install the part in the reverse order of removal with a new O-ring.
    Fig 7: Removing With A New O-Ring With Torque Specifications
    G03692708Courtesy of AMERICAN HONDA MOTOR CO., INC.
  19. Reconnect the rocker arm oil control solenoid (VTEC solenoid valve) 1P connector and rocker arm oil pressure switch (VTEC oil pressure switch) 2P connector.
  20. Connect a tachometer.
  21. Start the engine. Hold the engine speed at 3,000 RPM without load (in neutral) until the radiator fan comes on.
  22. Check the oil pressure at engine speeds of 1,000, 2,000 and 6,000 RPM. Keep measuring time as short as possible (less than 1 minute) because the engine is running without load.

    Is the oil pressure below 49 kPa (0.5 kgf/cm 2  , 7 psi)? 

    1. YES -  Go to step 23.
    2. NO -  Inspect the rocker arm oil control solenoid (VTEC solenoid valve) (see ROCKER ARM OIL CONTROL SOLENOID (VTEC SOLENOID VALVE) INSPECTION  ).
  23. Turn the ignition switch OFF.
  24. Disconnect the rocker arm oil control solenoid (VTEC solenoid valve) 1P connector.
  25. Attach the battery positive cable to the rocker arm oil control solenoid (VTEC solenoid valve) terminal.
  26. Start the engine, and check the oil pressure at 6,000 RPM.

    Is the oil pressure above 390 kPa (4.0 kgf/cm 2  , 57 psi)? 

    1. YES -  Go to step 27.
    2. NO -  Inspect the rocker arm oil control solenoid (VTEC solenoid valve) (see ROCKER ARM OIL CONTROL SOLENOID (VTEC SOLENOID VALVE) INSPECTION  ).
  27. With the battery positive terminal still connected to the rocker arm oil control solenoid (VTEC solenoid valve), measure voltage between ECM connector terminal C10 and body ground.
    Fig 8: Measuring Voltage Between ECM Connector Terminal C10 And Body Ground
    G03692709Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage above 5,000 RPM? 

    1. YES -  Go to step 28.
    2. NO -  Replace the rocker arm oil pressure switch (VTEC oil pressure switch).
  28. Turn the ignition switch OFF.
  29. Disconnect the battery positive cable from the rocker arm oil control solenoid (VTEC solenoid valve) terminal.
  30. Disconnect ECM connector B (25P).
  31. Check for continuity between ECM connector terminal B12 and body ground.
    Fig 9: Checking Continuity Between ECM Connector Terminal B12 And Body Ground
    G03692710Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES -  Repair short in the wire between the rocker arm oil control solenoid (VTEC solenoid valve) and the ECM(B12).
    2. NO -  Go to step 32.
  32. Connect the rocker arm oil control solenoid (VTEC solenoid valve) 1P connector terminal body ground with a jumper wire.
    Fig 10: Checking Connector Terminal Body Ground With A Jumper Wire
    G03692711Courtesy of AMERICAN HONDA MOTOR CO., INC.
  33. Check for continuity between ECM connector terminal B12 and body ground.
    Fig 11: Checking Continuity Between ECM Connector Terminal B12 And Body Ground
    G03692712Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES -  Substitute a known-good ECM (see HOW TO SUBSTITUTE THE ECM FOR TESTING PURPOSES ) and recheck. If the symptom/indication goes away, replace the original ECM (see ECM REPLACEMENT ).
    2. NO -  Repair a open in the wire between the ECM (B12) and the rocker arm oil control solenoid (VTEC solenoid valve).
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